Dog spikes have been used to hold rails down to wooden railway sleepers for a very long time and in some places they are still used. While they are cheap and simple they do not provide longitudinal restraint to the rail and additional rail anchors must be used for this.
In Europe an upgraded method of clamping the rail to the tie came into use which was made up of a steel plate (commonly called a K plate) under each rail and the plate was attached to the tie by the means of screw spikes. The rail in turn was clamped to the K. plate by means of two tee bolts in each plate which acted upon 2 clamps holding the rail down when the nuts on the captive tee bolts were tightened. However in spite of large spring washers underneath the nuts on the tee bolts they tended to work loose due to vibration in service. Men were employed to walk along the track and keep these bolts tight.
British patent 781406 discloses an elastic clip which was driven into the slot originally intended to hold the head of the tee bolts on the K plate and the toe of this clip acted on the top of the rail base and held it down thus eliminating the tee bolts and nuts. Patent 781406 was filed in October 1955 and in some parts of the world the clip is still being manufactured. It is known as the DE clip and although the patent shows it being made from round bar most of the clips are in fact made from 12 mm square bar with a 3 mm radius on each corner. The slot in the K. plate has a flat bottom with an upper surface comprising two sides each forming an arc and a slot between them to accommodate the tee bolt.
In some locations cast metal shoulders have been used in concrete ties which have a similar slot to the K. plate and were originally designed to accept the DE clip.
The K plate slot does not match the square bar used in the D E clip very well and the bar is not as high as the slot so the base of the clip takes up an angle as it is restrained in the slot. The forward part of the base bears on the top of the slot and the back of the base sits on the bottom of the slot. The front top part of the D E clip base is shaped to match the circular arcs on the top of the slot.
However this arrangement does not provide very good rotational location for the clip and in track when the clips are viewed from the top it is common to see the D E clip central axis out of alignment with the tie centre. This is often caused by track working machines such as ballast plows which apply indirect forces through the ballast to the sides of the clips. The misalignment tends to cause damage to the clips particularly when they are removed and a general loss of efficiency of the system which is eliminated by this new improved fastener which also has other important advantages.
U.S. Pat. No. 4,313,563 discloses an improved rail clip formed from metal plate with tapered legs. However because of the superior performance of the flat plate & tapered leg configuration the thickness of the material is much less than for the DE clip but since the height of the slot in the K plate is fixed this plate form of rail clip is not suitable for the K plate slot.
It is an object of this invention to provide a modification to the clip described in U.S. Pat. No. 4,313,563 so that it can perform effectively in slots of the K plate type. It is a further object of this invention to provide a rail clip that has a reduced tendency to rotate within the slot.